1. Technical Field
The present invention relates to a projector.
2. Related Art
A projector which includes an optical compensation element disposed on the light entrance side or on the light exit side of a light modulation device for increasing the contrast of a projection image is known (for example, see JP-A-2009-169042).
The technology disclosed in JP-A-2009-169042 uses a transmission type liquid crystal panel as the light modulation device.
According to this structure, the optical compensation element is so arranged as to be rotatable (the posture thereof is controllable) by a compensation element control mechanism around a rotation axis perpendicular to the optical axis of entering light and inclined to the vertical direction and the horizontal direction of the liquid crystal panel.
The compensation element control mechanism has a plate-shaped frame unit for supporting the optical compensation element, and a support holder for supporting the frame unit in such a condition that the frame unit can rotate.
The support holder has a plate-shaped first junction, a pair of side walls projecting toward the light exit side from the edges of the first junction opposed to each other, and a pair of second junctions projecting in such directions as to approach each other from the respective distal ends of the pair of the side walls.
The frame unit is inserted into a space between the first junction and the pair of the second junctions, and supported by the support holder in such a condition as to be rotatable with respect to the support holder around the rotation axis.
According to the technology shown in JP-A-2009-169042, the contrast of the projection image can be set at a desired level by the posture control of the optical compensation element. However, since the light entrance surface and the light exit surface of the light modulation device are exposed to the outside, adhesion of dust or the like to this light entrance or exit surface may occur. In case of adhesion of dust or the like to the light entrance or exit surface of the light modulation device, there is a possibility that the shadow of the dust or the like is produced on the projection image. In this case, projection of a high-quality image is difficult to be achieved.